1. Field of the Invention
The present invention relates to an endoscopic apparatus and more particularly, to an endoscopic apparatus which creates image information based on an image pickup signal from an electronic endoscope and which has a memory means for retaining the image information.
2. Description of the Related Art
Various kinds of endoscopes each using a solid-state image pickup device, such as a CCD (Charge-Coupled Device), have been recently proposed.
In such an endoscope, color image information is obtained in the following two methods: One is the simultaneous method in which a color separation filter is integrally formed with a solid-state image pickup device, and the other is the frame sequential method which sequentially switches light beams of three primary colors and supplies color information to a solid-state image pickup device. The detailed constructions of endoscopes which respectively use these methods are described in, for example, Japanese Laid-Open Patent No. Sho 51-65962 and Sho 55-54933.
The above-described conventional endoscope will be described with reference to FIG. 9.
Referring to FIG. 9, lamps 86 to 88 are lighted one-by one by a driving device 85 in a light source device 82, and condenser lenses 89 to 91 are disposed between the lamps 86 to 88 and the back end of a light guide 92 of an endoscope 81 so as to condense light beams from the lamps 86 to 88 onto the back end of the light guide 92. The lenses 89 to 91 each allow only a light beam of a single color, R, G or B, to pass therethrough. As a result, sequential light beams of R, G and B are condensed onto the back end of the light guide 92.
The light guide 92 passes through the endoscope 81, and radiates the R, G and B sequential light beams outward from the leading end of the endoscope 81. The radiated sequential light beams are reflected by an unillustrated object and form an image on the end face of a solid-state image pickup device 80 through an objective lens 93 mounted at the leading end of the endoscope 81. The formed optical image is photoelectrically converted into image pickup signals by the solid-state image pickup device 80, and the image pickup signals are transmitted to a control device 83 through a buffer amplifier 94 and converted into image information by a preprocess circuit 95 in the control device 83.
The R, G and B sequential image information is synchronized by a field memory 96, provided with processing, such as outline emphasis, by a postprocess circuit 97, and output to a display monitor 98, thereby displaying an unillustrated object image. Furthermore, if the transmission of the R, G and B sequential information to the field memory 96 is stopped by the preprocess circuit 95, a freeze image can be obtained.
However, the endoscopic apparatus having the above construction can retain image information for only one frame.
On the other hand, an endoscopic imaging system capable of retaining image information for a plurality of frames is disclosed in, for example, Japanese Laid-Open Patent Nos. Sho 59-69045 and Sho 59-69048 to the inventor of the present invention.
The endoscopic imaging system will be described with reference to FIGS. 10 and 11.
Referring to FIG. 10, an endoscopic imaging system 99 is comprised of an endoscope 100, an image pickup camera 101 disposed at the eyepiece of the endoscope 100, a control device 101 for conducting image processing on a picture signal from the image pickup camera 101, a light source device 103 for supplying illumination light to the endoscope 100, a large capacity memory device 104 and a small capacity memory device 105 each capable of storing image information from the control device 102, and a CRT monitor 106 for displaying the image information. Furthermore, a keyboard 107 and a light pen 108 are connected to the control device 102 to designate the contents of image information to be processed.
In the endoscopic imaging system 99 having such construction, an optical image obtained by the endoscope 100 is photoelectrically converted into image pickup signals by a CCD 107 in the image pickup camera 101, as shown in FIG. 11. The CCD 107 is driven by a driver 106. The generated image pickup signals are converted into picture signals by a process amplifier 108, and transmitted to the control device 102. The transmitted picture signals are converted into digital signals by a CPU 109, and retained in an image memory 110 as image information for one frame.
The CPU 109 outputs the image information to the CRT monitor 106 and retains the image information in the small capacity memory device 104 capable of storing image information for a plurality of frames and the large capacity memory device 105 capable of retaining the image information, both of which are disposed outside of the control device 102, as necessity requires. In response to the operation of the keyboard 107 and the light pen 108, the control device 102 executes various kinds of operations, for example, reading of the image information from the small capacity memory 104 or the large capacity memory 105, synthesizing this image information and image information from the image pickup camera 101 in the image memory 110 of the control device 102, and displaying the synthesized image information on the CRT monitor 106. The image information is transmitted through a bus 111.
However, at least a small capacity memory device and a control device are necessary to store or record and reproduce image information for a plurality of frames, and furthermore, the image information is required to be stored for the colors R, G and B, respectively, in order to achieve high-precision storage. Therefore, at least three signal cables and a plurality of cables for synchronizing signals and control signals are also necessary.
Furthermore, it is necessary to locate a designation device for designating the process contents to the control device, such as a keyboard, near a processing device.
Therefore, the endoscopic imaging system of the prior art requires a large number of complicated peripheral devices in order to store or record and reproduce image information for a plurality of frames.